Exchange Server 2007 Editions

Exchange Server 2007 is offered in two server editions: Standard Edition and Enterprise Edition.

•	Exchange Server 2007 Standard Edition is designed to meet the messaging and collaboration needs of small and medium corporations; it may also be appropriate for specific server roles or branch offices.
•	Exchange Server 2007 Enterprise Edition, designed for large enterprise corporations, enables creation of multiple storage groups and databases.

Exchange Server 2007 Edition Offerings
Feature	Standard Edition	Enterprise Edition
Storage Group Support	5 storage groups	50 storage groups
Database Support	5 databases	50 databases
Database Storage Limit	16 TB per database	16 TB per database
Single Copy Clusters	Not supported	Supported
Local Continuous Replication	Supported	Supported
Cluster Continuous Replication	Not supported	Supported

Clustering and High Availability

Exchange Server Enterprise Edition supports clustering of up to 4 nodes when using Windows 2000 Server, and up to 8 nodes with Windows Server 2003. Exchange Server 2003 also introduced Active/Active clustering, but for two node clusters only. In this setup, both servers in the cluster are allowed to be active simultaneously. This is opposed to Exchange's more common Active/Passive mode in which the failover servers in any cluster node cannot be used at all while their corresponding home servers are active. They must wait, inactive, for the home servers in the node to fail. Subsequent performance issues with Active/Active mode have led Microsoft to recommend that it should no longer be used. In fact, support for Active/Active mode clustering has been discontinued with Exchange Server 2007.

Exchange's clustering (Active/Active or Active/Passive mode) has been criticised because of its requirement for servers in the cluster nodes to share the same physical data. The clustering in Exchange Server provides redundancy for Exchange Server as an application, but not for Exchange data. In this scenario, the data can be regarded as a single point of failure, despite Microsoft's description of this set up as a "Shared Nothing" model. This void has however been filed by ISV's and storage manufacturers, through "site resilience" solutions, such as geo-clustering and asynchronous data replication.

Exchange Server 2007 introduces new cluster terminology and configurations that address the shortcomings of the previous "shared data model".

Exchange Server 2007 now provides built-in support for asynchronous replication modeled on SQL Server's "Log Shipping" in a CCR (Cluster Continuous Replication) clusters, which are built on MSCS MNS (Microsoft Cluster Service - Majority Node Set) clusters which do not require shared storage. This type of cluster can be inexpensive and deployed in one, or "stretched" across two datacenters for protection against site wide failures such as natural disasters. The limitation of CCR clusters is ability to have only two nodes and the third node known as "voter node" of file share witness that prevents "split brain" scenarios, generally hosted as a file share on a Hub Transport Server. Second type of clusters is the traditional clustering that was available in previous versions, and is now being referred to as SCC (Single Copy Cluster). In Exchange Server 2007 deployment of both CCR and SCC clusters has been simplified and improved where the entire cluster install process takes place during Exchange Server install. LCR or Local Continuous Replication has been referred to as the "poor man's cluster". It is designed to allow for data replication to an alternate drive attached to the same system and is intended to provide protection against local storage failures. It does not protect against the case where the server itself fails.

In February, the Microsoft Exchange team announced they are wrapping up the beta release of SP1 for Exchange Server 2007. It was announced that SP1 will include an additional high avabilibity feature called SCR (Standby Continuous Replication). Unlike CCR which requires that both servers belong to a Windows cluster, typically residing in the same datacenter, SCR can replicate data to a non-clustered server, located in a separate datacenter.

Exchange Server 2007

For some time after the release of Exchange 2003, Microsoft's future plans for the product were not known. Edge Services, an add-on for the main product, was to have been released sometime in 2005 but was dropped. The new version, Exchange 2007, was released on DVD in late 2006 to business customers as part of Microsoft's rollout wave of new products. It includes voice mail integration, better search and support for Web services, better filtering options, and a new Outlook Web Access interface.

Exchange 2007 will run on 64-bit x64 version of Windows only, pointing out the substantial performance benefits that 64-bit computing brings to the product. This limitation applies to supported production environments only; a 32-bit trial version is available for download and testing. However, companies currently running Exchange on 32-bit hardware will be forced to replace or migrate hardware if they wish to upgrade to the new version. Even those companies that are currently running Exchange on 64-bit capable hardware will still need to upgrade their server operating system simultaneously with the Exchange 2007 upgrade.

The first beta of Exchange 2007 (then named "Exchange 12") was released in December 2005 to a very limited number of beta testers. A wider beta was made available via TechNet Plus and MSDN subscriptions in March 2006 according to the Microsoft Exchange team blog,

On April 25, 2006, Microsoft announced that the next version of Exchange would be called Exchange Server 2007. More details about Exchange Server 2007 can be found at the Exchange Preview Website. This site has information about this version of Exchange and outlines key improvements:

• Protection: anti-spam, antivirus, compliance, clustering with data replication, improved security and encryption
• Improved Information Worker Access: improved calendaring, unified messaging, improved mobility, improved web access
• Improved IT Experience: 64-bit performance & scalability, command-line shell & simplified GUI, improved deployment, role separation, simplified routing
• "Exchange Management Shell": a new command-line shell and scripting language for system administration (based on the Windows PowerShell scripting language -- formerly called "Monad" -- developed for Windows Vista). Shell users can perform every task that can be performed in the Exchange graphical user interface plus additional tasks, and can program often-used or complex tasks into "scripts" that can be saved, shared, and re-used.
• "Unified Messaging" that lets users receive voice mail, e-mail, and faxes in their mailboxes, and lets them access their mailboxes from cell phones and other wireless devices. Voice commands can be given to control and listen to e-mail over the phone (and also send some basic messages, like "I'll be late")
• Removed the database maximum size limit. Database size is now limited by hardware capability and the window for backups and maintenance.
• Increased the maximum number of storage groups and mail databases per server, to 5 each for Standard Edition (from 1 each in Exchange 2003 Standard), and to 50 each for Enterprise Edition (from 4 groups and 20 databases in Exchange 2003 Enterprise).